I think it’s reasonable to differentiate between the likes of Carnegie and present day people like Bill Gates who basically set up enterprises that became hugely successful and company directors and CEOs, who are effectively employees.Let's not forget that history teaches us there has been examples of wealth inequality since the beginning of civilizations. This is nothing new. Europeans peasants and serfs were infinitesimally poorer than nobles and kings. In the late 1880s Andrew Carnegie was worth what would be $4.8B according to this article.
The Gilded Age Family That Gave It All Away: The Carnegies
At the same time, his unskilled laborers in the steel mills earned about $600 year for 12 hour, 7 days a week work, equal to less than $18,000/year, although this article says the earned less during the Great Depression.
Life In The Pittsburgh Steel Mills Was Hell On Earth
Certainly a great income disparity was present then.